Abstract: The present invention relates to bacteria-derived extracellular vesicles having reduced toxicity and the use thereof and, more specifically, to a pharmaceutical composition for treating or diagnosing diseases, a composition for delivering materials and a vaccine composition comprising bacterial extracellular vesicles having reduced toxicity, a method for preparing same, and the like. By using the bacterial extracellular vesicles having reduced toxicity of the present invention, in vivo or in vitro side effects can be reduced, efficacies can be increased, and thus the stability and efficacies of a therapeutic agent or a diagnostic agent, for various diseases including cancer, a drug carrier and/or a vaccine carrier can be enhanced. The bacterial extracellular vesicles having reduced toxicity and having loaded materials for disease treatment or vaccine, and a method for preparing same can he used for in vitro or in vivo treatments, drug carriers, vaccines or experiments.